Transmission line maintenance derrick



April l5, 1958 T. R. BILL TRANSMISSION LINE: MAINTENANCE DERRICK Filed Jan. 21, 1955 NN N -V llllvl 1| lN VEN TOR.

14%/07'72 eig United States Patent O TRANSMESSION UNE MAINTENANCE DERRICK vfheotiore R. Bill, San Leandro, Calif.

Application January 21, 1955, Serial No. 483,332

6 Claims. (Cl. 212-8) This invention relates to improvements in means for handling transmission line equipment and materials and has particular reference to a derrick for setting and removing poles, transformers, cross-arms, and other heavy or cumbersome devices and elements, and provides a derrick which is peculiarly adapted for mounting on the top of a maintenance truck, and which will fold flat on the top when not in use, and which, because of the speciic arrangements and auxiliary devices, permit the boom to be lowered to a greater degree than is now possible with derricks of this type.

Though this derrick can be mounted on any support, such as an ordinary truck bed, it is most advantageously used when mounted on a truck top, thus providing greatly increased reach with a derrick which folds back substantially within the length of the truck top, and if the auxiliary elements connected therewith are used in connection with the transmission line maintenance derrick disclosed in my copending application, Serial Number 451,556, tiled August 23, 1954, an exceptionally long reach is available because of the extensible boom covered by that application, other than the extensible feature, the structure being substantially the same, though the mounting of the boom in that application is different in that the boom support pivots are in a plane above the pivots for the elevating and lowering motors.

The objects and advantages of the invention are as follows:

First, to provide a line maintenance truck with a derrick which will fold flat on top of the truck when not in use, and which, when in use can be lowered to a greater degree than other known types.

Second, to provide a derrick as outlined with a hydraulic motor cooperative with the folded boom for providing an initial lift for subsequent control by the boom controlling motors.

Third, to provide a derrick as outlined in which the boom lifting motor is in circuit with the boom controlling motors so as to require a single manual control for continuous operation through lift and control.

In describing the invention reference will be had to the accompanying drawings, in which:

Fig. l `is a side elevation of a maintenance truck shown in phantom with the invention applied thereto.

Fig. 2 is a top plan View of Fig. l.

Fig. 3 is a vertical section through the lift motor.

The boom may be of the extensible type shown in the previously mentioned copending application or may consist of any other type, and is shown as being formed of a length of tubing having a sheave 11 pivotally mounted in a sheave head 12 at one end, for the hoisting cable 13, and with the other end lixed to a cross member 14 as indicated at 15 such as by welding, this cross member also being formed of a length of tubing and being pivotally supported in the bearings 16 and 17 as indicated at 18, and struts 19 and 2t) also formed of tubing are xed to the sides of the boom and extend almost to the ends ice ofthe cross member to which they are lixed at 21 and 22, the bearings having suitable extensions 23 for support by the truck, and are mounted at the rearward end of the truck.

Mounted in spaced relation forwardly of the bearings 16 and 17 are the hydraulic motor bearings 24 and 25 which are also suitably mounted on the truck, the bearings 16 and 24, and 17 and 25, being respectively ixedly connected by the reach bars 26 andl 27.

The hydraulic boom control motors include each a cylinder 28 and a` plunger 29, these cylinders having their lower ends pivotally connected to the bearings 24 and 25 as indicated at 30, while the terminal ends of the plungers are pivotally connected to the sides of the boom as indicated at 31, these connections all being rather free to compensate for the swing inward when the boom is folded on the truck top, as indicated at 28.

@ne of the most important features of the invention exists in the relative locations of the pivots for the boom and boom motors, the pivots 30 for the boom motors being on a relatively higher plane than the boom pivots 18, therefore, when fluid under pressure is transmitted to the boom motors, the motor tends to force the boom downward as` is clearly evident from the relative angularities of the folded boom 10 and the boom motors 28', therefore the boom motors cannot raise the boom from the folded position, for which reason a boom lifting motor is supplied, and consists of a cylinder 32 which is mounted at the forward end of the truck and almost entirely enclosed within the body of the truck as indicated, any suitable mounting means being used as indicated in one form at 33.

This lifting motor has a piston 34 and a plunger 35 which operates through a head 36 and which head requires no sealing means. This plunger terminates in a cradle 37 for the portion of the boom above the pivots 31.

As will be readily apparent, because of the location of the boom motor pivots 30 in a plane above those of the boom pivots 18, the sheave end of the boom can be lowered to a greater degree than when they are oppositely located as in the previously mentioned copending application, the higher the pivot 30 as related to the pivot 18, the greater the degree of lowering of the sheave end, which is quite important in maintenance work. Obviously, the boom control motors cannot raise the boom until the lifting motor has raised the boom to where the pivots 31 are above the axis across the pivots 18 and 30.

A simplified operating diagram is incorporated in Fig. l, in which a four-way valve 38 controls the three motors, the boom control motors having connections at both top and bottom of the cylinders as indicated at 39 and 40, while the boom lifting motor has only a bottom connection 41.

With the valve in the position shown, fluid is delivered 28 and the lower end of the boom lifting cylinder are` connected through the line 45 and connection 46, through the valve 38 and line 47 to the supply tank 48 which is in communication with the pump through the line 49. Sincethe fluid under pressure is only applied to the upper ends of the boom control cylinders, the boom lifting cylinder is maintained under pressure with the plunger 35 and its cradle maintained in the advanced position shown. When the boom is retracted to rest in the cradle, the pressures become substantially equalized, and the plunger settles.

down to where the boom is in the position indicated at 10. and lowered through control by this valve.

As will be noted, the boom is also merely raised'-` When the boom is to be raised to operative position, the valve 38 is moved to the other position through 90 degrees. The tluid under pressure is then delivered from the pump tothe connection 4 6, thence to` theline 45 whichis in communication with the lower end ofthe boom lifting cylinder 32 and also with the lower ends of the boom control cylinders through the cross connection 50. The reaction is to force the boom downward as is plainly evident from the reclined position shown dotted, therefore the full pressure is applied through the boom liftingl cylinder which raises theY boom well past the dead center through the respective pivots 18, 30 and 31 at which time the boom control cylinders 23 take over and swing the boom to its operative position, the fluid flowing from the upper ends of the cylinders 28 through the line 43, valve 38, and line 47 to the supply tank 48, the plunger 35 being maintained under pressure and therefore being maintained in the advanced position shown until the booni is again retracted to the reclined or folded position.

I claim:

l. A folding derrick comprising, a support having a front end and a rear end, transversely spaced boom support bearings on said support adjacent the rear end, a motor support bearing spaced forwardly from and in an elevated plane above each of said hoorn support bearings, a boom pivotally supported at one end by said boom support bearings, a fluid motor for each motor support bearing and each having a cylinder and a plunger and pivotally connected at one end to the other end of said boom and pivotally supported at their other ends by said motor support bearings, and control means for said uid motor for advancing said boom to an operative position overhanging said rear end and to a reclined position on said support, and a lifting motor having a cradle cooperative with the other end of said boom when in reclined position and located forwardly of said motor support bearings and including said control means for raising said boom to an inclination above dead center as related to the respective pivotal connections for the boom and iluid motors for transfer of operation of the boom to said duid motors after said boom has passed said dead center, the relative planes of said boom support bearings and said motor support bearings increasing the degree of available overhang and lowering of the boom during operation thereof.

2. A folding derrick comprising, a support, a boom having one end pivotally supported adjacent one end of said support, power means pivotally connected at its respective ends to the other end of said boom and to a point in spaced relation on said support toward the other end and in a plane above the plane of the pivotal support for the boom for controlling operation of said boom in overhanging relation to said one end of said support and for retracting said boom to a reclined position on said support with the reaction of said power means on said boom being downward when the boom is in fully reclined position and the relative planes of the respective pivotal supports and connections thereby increasing the available degree of lowering of the boom in overhanging operative position, and raising means supported by said support and cooperative with the other end of said boom in reclined position for raising said boom above the dead center of the respective pivotal supports and connections for continued raising and operation of the boom by said power means, and control means for said power means and raising means.

3. A truck having a top having a front end and a rear end, a boom having one end hingedly mounted adjacent said rear end, two liuid motors each having a cylinder and a plunger with the cylinders hingedly mounted on said'top in spaced relation forwardly from the hinged mountings for said boom and in a plane above said hinged mountings for said boom, and having their plungers pivotally connected to the respective sides adjacent the other end of the boom, and a fluid motor mounted at the front end of said top and having a cradle cooperative with the other end of said boom when in reclined position for raising the reclined boom to an inclination above the dead center through the hinged mountings and pivotal connections for further raising and operation of said boom by said uid motors.

4. A truck having a top having a front end and a rear end, transversely spaced boom bearings projecting above said top adjacent said rear end, transversely spaced motor support bearings in spaced relation forwardly from said boom bearings and projecting upwardly to a plane above the plane of said boom bearings, a boom having one end pivotally supported in said boom bearings, two fluid motors each having a cylinder and a plunger with the respective cylinders pivotally supported by the respective motor support bearings and with the plungers pivotally connected to the respective sides adjacent the other end of said boom, a fluid jack having a cylinder and a piston and mounted at the front end of said top and cooperative with said boom when reclined forwardly on said top for raising said boom from a fully reclined position to an inclination above the dead center through said boom bearings, motor support bearings, and pivotal connections for further operation by said fluid motors, said boom bearings and motor support bearings located in respective higher planes providing for increased degree of lowering of the boom in operative position and creating downward thrust to the reclined boom with the tiuid jack overcoming said downward thrust for raising and operation of the boom. n

5. A structure as defined in claim 4; a supply of iiuid under pressure for said fluid motors and uid jack, and unitary manual control means for simultaneous and mutual operation of said liuid motors and fluid jack for initial operation by the liuid jack with operation automatically transferred to the fluid motors following passing of said dead center from the reclined position of the boom.

6. A folding derrick comprising a support, a boom having its lower end pivotally mounted on one end of said support, uid motor bearings mounted on said support in spaced relation toward the other end of said support and having a common axis in a plane above that of the pivotal mounting for the boom, a boom operating fluid c motor for each fluid motor bearing and having one end pivotally connected thereto with the other end pivotally connected to the upper end of the boom for advancing and retracting said boom relative to the perpendicular and for reclining said boom, and a lifting iiuid motor cooperative with the upper end of said boom in reclined position for raising said upper end to a position above dead center as related to the planes of the axis of the pivotal mounting for the boom and of the iiuid motor bearings for continued operation of the boom by said boom operating iiuid motors, and single control means for sequential operation of said lifting fluid motor and said boom operating uid motors.

References Cited in the tile of this patent UNITED STATES PATENTS 387,887 Kalinski et al Aug. 14, 1888 2,336,965 Shoemaker Dec. 14, 1943 2,598,517 Drott May 27, 1952 2,687,809 Balogh Aug. 31, 1954 

